[Info-vax] question on HBVS and SHOW DEVICE

[Phillip Helbig---undress to reply]

In article <nospam-D26979.15262303102013 at news.chingola.ch>, Paul Sture
<nospam at sture.ch> writes: 

> In article <l2j9o9$gtv$1 at online.de>,
>  helbig at astro.multiCLOTHESvax.de (Phillip Helbig---undress to reply) 
>  wrote:
> 
> > Consider the output from SHOW DEVICE/FULL below.  Question: why does the 
> > "shadow set virtual unit" appear for one of the disks but not the other 
> > two?  (For what it's worth, all disks are physically identical.)
> > 
> > Does it appear if the disk (shadow member) in question does not have a 
> > direct connection to the node on which the command is issued?
> > 
> > Disk DSA510:, device type Generic SCSI disk, is online, mounted, 
> > file-oriented
> >     device, shareable, available to cluster, error logging is enabled, device
> >     supports bitmaps (bitmaps active).
> > 
> 
> <snip>, physical volumes follow:
> 
> >   Volume is also mounted on LEEBIG, MINNIM.

>From which one can conclude that the command was issued neither on 
LEEBIG nor on MINNIM (it was issued on JANDER).

> > Disk $110$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
> >     DSA510:, served to cluster via MSCP Server, error logging is enabled.

> > Disk $150$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
> >     DSA510:, shadow set virtual unit, error logging is enabled.

> > Disk $170$DKB400:, device type DEC RZ2ED-LS, is online, member of shadow set
> >     DSA510:, shadow set virtual unit, error logging is enabled.

> Correction: "shadow set virtual unit" appears for the last 2 disks 
> listed but not the first.  

Right.

> The first disk is "served to cluster via MSCP 
> Server" which implies that there is a direct path from the host to the 
> second and third disks but the first is physically connected to another 
> system and is visible via MSCP.

It's actually the opposite.  This is a 3-member shadow set:

Device                  Device           Error    Volume         Free  Trans Mnt
 Name                   Status           Count     Label        Blocks Count Cnt
DSA510:                 Mounted              0  USER          11950256    99   3
$110$DKB400:  (JANDER)  ShadowSetMember      2  (member of DSA510:)
$150$DKB400:  (LEEBIG)  ShadowSetMember      0  (member of DSA510:)
$170$DKB400:  (MINNIM)  ShadowSetMember      0  (member of DSA510:)

All disks on my system have a direct connection to only one node.  So, 
there is a direct path from JANDER (where the command was issued) to 
$110$DKB400:.  The other two disks are visible to JANDER via MSCP.